Novel antibody polymer reagents for SARS-CoV-2 detection

项目总结 迫切需要在临床和非临床环境中快速检测SARS-CoV-2病毒，包括 护理地点、工作场所和家庭，其灵敏度和特异度与RT-PCR相当或更好 冠状病毒2RNA的检测。大部分人与人之间的CoV-2传播发生在感染者之前 出现症状。这一重要的有症状前/无症状的CoV-2传播宿主要求 在全人群筛查范围内有效识别感染者及其接触者，以预防 新冠肺炎疾病的爆发，同时使社会得以开放，经济得以复苏。这个级别的 还需要进行监测，以充分评估对策的有效性，包括疫苗和 治疗。我们将开发一类新的诊断产品试剂，抗体聚合物，以创造产品 可在人群筛查规模上生产并用于快速检测CoV-2抗原 提高了灵敏度，接近于CoV-2基因组RNA的金标准RT-PCR检测的灵敏度。 我们的抗体聚合物将通过设计一种新的小的、稳定的、单一的多肽抗体素来生产 冠状病毒-2抗体称为可变淋巴细胞受体(VLRs)作为聚合物实现基本不可逆 与CoV-2病毒结合。VLR聚合物与所有诊断免疫分析形式兼容，包括侧向 流动分析(LFA)“试纸”，这可能是在非实验室环境中首选的，并已建立 信号方式，例如胶体金和辣根过氧化物酶(HRP)。VLRs是一种抗原性受体 无颌脊椎动物(七鳃鳗和七鳃鳗)由高度多样化的富含亮氨酸的重复结构域组成， 唯一已知的抗原特异性免疫受体不是免疫球蛋白(IGs)。VLRS的结合部位 包含在一个小的单一多肽中，并由刚性的β-折叠中的氨基酸残基组成 形成VLR结构的凹面。Jawed和Jawed的超过5亿年的进化分离 无颌脊椎动物和VLR抗体独特的抗原结合部位结构已被证明是 不同于常规免疫球蛋白抗体的新的特异性。CoV-2病毒的外膜由 多价阵列的尖峰蛋白(S)是多价的、基本上不可逆的结合的理想靶点(S)， 通过适当的多价结合剂。我们将在基因上串联编码VLR和结合的基因 冠状病毒2型S蛋白产生偶联冠状病毒结合的多价VLR型聚合物结合剂的特异性 2个抗原，以获得可放大的、可见的结果，例如颜色变化。冠状病毒2型S蛋白50的高比例 -每个病毒颗粒100个S蛋白三聚体，以单拷贝冠状病毒2RNA基因组，并可扩增 通过催化，例如HRP，提供了显著提高的CoV-2抗原检测灵敏度 RT-PCR检测单拷贝CoV-2RNA获得的灵敏度。

PROJECT SUMMARY There is an urgent need to rapidly detect SARS-CoV-2 (CoV-2) virus in clinical and nonclinical settings, including point of care sites, workplace, and home, at sensitivity and specificity comparable or superior to RT-PCR detection of CoV-2 RNA. Much of the person-to-person CoV-2 transmission occurs before infected individuals develop symptoms. This significant pre-symptomatic/asymptomatic reservoir of CoV-2 transmission mandates efficient identification of infected individuals and their contacts at population-wide screening scale to prevent outbreaks of Covid-19 disease while allowing societies to open and economies to recover. This level of surveillance will also be needed to fully evaluate the effectiveness of countermeasures, including vaccines and therapies. We will develop a new class of diagnostic product reagents, antibody polymers, to create products that can be produced and used at population screening scale for rapid CoV-2 antigen detection at significantly improved sensitivity that approaches the sensitivity of :gold-standard” RT-PCR detection of CoV-2 genomic RNA. Our antibody polymers will be produced by engineering a novel class of small, stable, single polypeptide anti- CoV-2 antibodies termed variable lymphocyte receptors (VLRs) as polymers to achieve essentially irreversible binding to CoV-2 virus. VLR polymers are compatible with all diagnostic immunoassay forms, including lateral flow assay (LFA) “dipsticks”, which is likely to be preferred in non-laboratory settings, and with established signaling modalities, e.g., colloidal gold and horseradish peroxidase (HRP). VLRs, the antigen receptors of jawless vertebrates (lamprey and hagfish), are composed of highly diverse leucine-rich repeat domains and are the only known antigen-specific immune receptors that are not immunoglobulins (Igs). The binding site of VLRs is contained within a small single polypeptide and comprised by amino acid residues in the rigid beta-sheets that form the concave surface of the VLR structure. The over 500 million year evolutionary separation of jawed and jawless vertebrates and distinctive antigen-binding site structure of VLR antibodies have proved a source of novel specificities distinct from conventional Ig antibodies. The outer envelope of the CoV-2 virus is composed of a multivalent array of spike (S) protein that is an ideal target(s) for multivalent, essentially irreversible binding, by appropriately multivalent binding agents. We will genetically link in tandem genes encoding VLRs with binding specificity for CoV-2 S protein to create such multivalent VLR polymer binding agents that couple binding of CoV- 2 antigens to an amplifiable, visually observable result, e.g., color change. The high ratio of CoV-2 S protein 50 – 100 S protein trimers per virus particle, to the single copy CoV-2 RNA genome, and the amplification available via catalysis, e.g., HRP, provides significantly improved CoV-2 antigen detection sensitivity that approaches sensitivity achieved with RT-PCR detection of single copy CoV-2 RNA.